diff --git a/src/qibochem/ansatz/basis_rotation.py b/src/qibochem/ansatz/basis_rotation.py
index 5926a50..a533d33 100644
--- a/src/qibochem/ansatz/basis_rotation.py
+++ b/src/qibochem/ansatz/basis_rotation.py
@@ -3,7 +3,6 @@
 """
 
 import numpy as np
-
 from qibo import gates, models
 from scipy.linalg import expm